Summary With this submission of a competitive renewal application of our training grant titled ?Graduate Training in Cancer Research?, we are seeking five years of support for a Training Program that has been continually funded since 1975. Since that time, more than 500 physicians and physician-scientists who were part of fellowship training programs in medical oncology and, initially, pediatric oncology at the Dana-Farber Cancer Institute received, through this funding mechanism, the essential support and protected time that they required to launch an academic career. Of the 114 trainees who have been supported by this training program during the past 15 years, 18 continue as fellows. Of the remaining 96, 95% presently hold full-time academic positions at medical centers throughout the United States and 92% have received independent funding. With the present application, we seek to continue this tradition of training leaders in academic oncology. The future of cancer research will continue to depend on the continued training of highly-talented and creative physician-scientists who possess an understanding of the clinical aspects of neoplastic disease, are able to apply these concepts to appropriate laboratory issues or health services within the many areas of tumor biology and population sciences, and emerge as academic leaders with sufficient skills to direct research programs, patient care, and educational efforts. The development of such individuals can only be accomplished within an environment where physicians and scientists work in physically adjacent areas, exchanging ideas and collaborating on a wide array of endeavors. The program will build on a foundation of excellence in Medical Oncology established during clinical training in the Dana-Farber/Partners CancerCare Hematology/Oncology Fellowship Program. All of these candidates have already received an MD or MD/PhD degree, completed 2 or 3 years of Internal Medicine residency, and at least one year of clinical training in Medical Oncology. Some trainees may have also completed an additional 6 months of training in Hematology. The training grant program will select the most highly qualified candidates from this pool who wish to pursue laboratory research or clinical investigation at the Dana-Farber Cancer Institute or nearby surrounding institutions. The program will provide outstanding mentored laboratory and clinical investigation research experiences from senior and experienced junior faculty and support for the recruitment and mentorship of under-represented minority fellows. It is expected that at the conclusion of their training, those individuals supported by this training program will have the ability to design, initiate, and complete individual clinical or laboratory research projects, will be able to function independently or with minimal supervision, and will be positioned to soon establish themselves as independent research investigators.